PrxCa1-xMnO3 (PCMO) metal oxide is difficult to etch using a dry etching processes. It has been reported that dry etching of PCMO using chemistries of chlorine and argon is somewhat workable, but the etch rate is very low and very little of the mask survives the etching process, leading to etching of portions of a device where etching is not desired. It has also been reported that dry etching using pure argon to sputter etch the PCMO thin film has had some success, however, the same problem of poor selectivity of the PCMO thin film vs the mask material is present and unwanted etching of an underlying layer occurs.
A two-step, or multiple step, process has been used in the prior art, however, such techniques do not stop etching once the bottom electrode is reached, and results in residue being left on the stack sidewall, which residue is a direct result of etching the bottom electrode.